The objectives of the Conference on the Scientific Basis for Respiratory Therapy are to: 1) assess existing data concerning the efficacy of various modes of respiratory therapy in the treatment of patients with steady state chronic obstructive lung disease; 2) to indicate the additional data needed to more adequately assess the various modes of therapy; and 3) to make these findings available to the National Heart and Lung Instutute and to the lung community in order to stimulate appropriate investigations. The format for the Conference will be a two and one-half day workshop meeting inviting the best investigators and clinicians available to participate. The scope of the workshop will be divided into four areas: 1) intermittent positive pressure-breathing therapy; 2) aerosol therapy, both bland and pharmacologically active; 3) oxygen therapy; and 4) physical therapy, excluding systemic exercise. It is intended that this Conference will be a stepping stone to implementation of the "Report of the NHLI Task Force on Problems, Research Approaches, and Needs in Respiratory Diseases." The Conference Planning Committee will hold a special session for young investigators at the 1974 Annual Meeting of the American Thoracic Society to bring to their attention the specific areas identified by the Conference needing further investigation. The papers presented at the Conference and the evaluation of the modes of therapy, with indications for specific areas for research, will be published as a supplement to the "American Review of Respiratory Disease" and made available to the NHLI and the entire lung community. It is believed that this Conference will expedite implementation of the NHLI Task Force Report.